1. Field of the Invention
The present invention relates to a display device including a transistor which includes an oxide semiconductor.
2. Description of the Related Art
A technique by which transistors are formed using semiconductor thin films over a substrate having an insulating surface has been attracting attention. The transistor is used in a wide range of electronic devices such as an integrated circuit (IC) and a display device. A silicon-based semiconductor material is widely known as a material for a semiconductor thin film which can be used in a transistor. As another material, an oxide semiconductor has been attracting attention.
For example, a technique for forming a transistor using zinc oxide or an In—Ga—Zn—based oxide semiconductor as an oxide semiconductor is disclosed (see Patent Documents 1 and 2).